Free tool
HTTP header checker
Enter a URL and we'll show you every header it returns.
Reads every response header a URL returns and scores the six security headers worth having. It also catches X-Robots-Tag noindex — a way of deindexing a page that never appears in the HTML.
How it works
- 1
We request the URL and read the complete response header set.
- 2
Six security headers are checked: HSTS, CSP, X-Content-Type-Options, Referrer-Policy, Permissions-Policy and X-Frame-Options.
- 3
Cache-Control and X-Robots-Tag are called out separately, because both change how the page behaves in ways nothing on the page reveals.
Questions about this tool
- Why does X-Robots-Tag matter so much?
- Because it deindexes a page without leaving any trace in the HTML. If a page has vanished from search and the source looks fine, this header is the first thing to check.
- Do security headers affect SEO?
- Not directly. They affect whether your site can be framed, whether a browser will guess a file's type, and how much of your URLs leak to third parties — worth having on their own merits.
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